Spillway



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- SPILLWAY Filed Jan. 5,. 1925 7 eets-sh 3 am A MEYER,

IN YENTOR Br @aMQ Paul- .0

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A. F. MEYER SPILLWAY Filed Jan. 5, 1925 M" I N VENTOR ADaLPH fi MEYERFeb. 23 ,1926. A. F. MEYER SPILLWAY 7 Sheets-Sheet 5 Filed Jan. 5, 1925l/vvz/vro/e flDoLPH fr MEYER Feb. '23 1926.

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- A. F. MEYER I SPILLWAY Filed Jan. 5, 1925 mul 7 Sheets-Sheet 7' Brvulva A TToRA/E Y6 Patented Feb, 23, 1926.

PATENT titFFlClil.

SPILLVAY.

Application filed January 5, 1925. Serial No. 615.

To all whom it may co'nccm:

'Be it known that I, Anonrrr F. Merlin, a citizen of the United States,resident of St. Paul, in the county of Ramsey and State of'Minnesota,have invented certain new and useful Im rovements in Spillways, of whichthe following is a specification.

This invention relates to an improved spillway as well as to the novelmethod of designing and building the spillway.

at, present practically all spillways are built according to the ogeeprofile and with a curvature to cause the overfalling water to bedischarged in a horizontal direction. The fillet or bucket at the toe ofthe dam or spillway is usually provided to assure thishorizont-aldeflection of the discharged sheet for the ostensible purpose ofprotecting the bed of the stream against undercut ting and erosion atthe lower end of the toe particularly when severe floods are passedrInsuch )resent spillway designs,

scour and uplift under the apron are cominon sources of trouble. Upliftoccurs when thetailrwater below the spillway (the terms overfall dam,weir and dam with crest gates are to be understood as included in theterm persists for long distances downstream from present spillwaystructures, which necessitates long andexpensiye aprons, cribs,inattresses, riprap or other forms of ri "er Jed protection. Theoverfalling water follows the profile of the present-day spillwayand,since the line of action of the cynamic presthan the line of action ofthe static back-pressure of the tail-water,

a couple is formed causing rotation and hence the formation of largeeddy on top of the swiftly moving water. In this case the surfacecurrents beyond the spillway are ba kward for a considerable. distancedown- 11, high velocities usually persist in the r currents until beyondthe end of the dee apron anc scour continues, whereby expensive repairsare necessitated.-

Among those skilled in the art to which this invention relates thereappears a pres-' what may be termed a hollow bucket, that is, the bucketor curved face of the fore slope at the downstream toe of the spillway,is recessed or hollowed to provide a basin whose dimensions aresubstantially corre' lated with the height of the dam, the amount ofoverflow, and the natural depth of the tail water below the dam. Thespillway is constructed preferably so as to lead the water, just beforeit enters the pool provided by the hollow bucket, in as nearly avertical direction as its initial horizontal velocity and the structuralfeatures of the design permit. By doing so, the dynamic pressure of theoverflowing water is exerted tore nearly directly in opposition to thestatic pressure of the pool. In consequence, the swiftly moving water isquickly slowed up, the surface eddy is greatly reduced in size, and thewater acquires a downstream direction of motion throughout the fulldepth of the natural stream within a short distance from the toe of thedam.

A feature of the novel invention, which it is desirable to use in mostspillways, resides in the shaping of the hollow bucket to provide aportion which extends in an upstream direction underneath the frontslope or face of the spillway. This bucket portion permits the formationof a back eddy behind the swiftly flowing water, so thatthc overfallingwater is attacked on the underside and more rapidly retarded.

Another novel feature, above suggested, consists in the properdimensioning of the hollowrbuckot in correlation with the energypossessed by the overfalling water as it enters the bucket substantiallyat the elevation of the center of gravity of the tailwater. Atthe footof the fall the swiftly moving water is capable of exerting a continuouspressure in the direction otits motion equal to its mass times itsvelocity. This is known as the dynamicpressure of the flowing water. Inaddition, this water exerts a static pressure in every directionproportional to its depth. This latter pressure of the swiftly movingwater is usually very small in proportion to the former. To slow up theswiftly moving water and to destroy its excess energy so that it willflow down the natural channel again at the same depth and velocity as itdid before the dam was built, it is necessary to apply to it a staticbaclzqnessurc at least substantially equal to the dynamic pressure plusthe static pressure of the swiftly moving water minus the residualdynamic pressure which the waterpossesses in a downstream directionafter it has been slowed up. The greater thestatic baclepressureprovided and the more eti ectirely it applied to tlie swiftly movingwater, the more quickly will that water be robbed of its excess energy.The depth oi. water which provides this necessary static back-pressureis herein designated by the capital letter D and is made the principalbasis for the dimensioning ot the novel hollow bucket. Hence, for sakeof clarity and brevity, such letter B is, in the specification andclaims, employed to des nate and spcciiy such linear dimension.

The object therefore of the invention is to provide an improved spillwayand method of designing and building); the same.

Other objects of the invent-ion will appear from the followingdescription and the accompanying d "awinp's and will be pointed out inthe annexed claims.

In the accompanying dra ings there have I been disclosed a series ofstructures designed to carry out the objects of the invention but itisto be understood that the invention is not confined to the exactfeatures shown as various changes may be made within the scope of theclaims which follow.

In the drawings:

Figure 1 is a vertical sectional view through a spillway constructed inaccord ance with the invention, the spillway being of the hollow typeand of medium or average height;

Figure 2 a vertical sectional view of a low solid-type of spillwayembodying the invention and adapted to a very large discharge;

Figure 3 is a view of a spillway similar to that shown in Figure 1 butof the solid type and adapted to a larger discharge;

Figure 4 is a similar view through a solid spillway of the high typeshowing the invention as applied thereto;

Figure 5 is a solid spillway of the type employing gates and adapted toa relatively large discharge;

those buttresses or cross-walls are evaese ing the invention in suchfull, concise and exact terms as to enable any person skilled in the artto which it up Jertains, to carry out the method and to construct anduse spillways, embodying the invention.

The invention is shown in Figure 1 as applied to a well-known form ofdam or spillway ot the hollow type which is preterably of concreteconstruction, desirably steel-reinforced, as this is the most practicalmaterial for construction and one with which those skilled in this artare most familiar, although it-is to be understood that otherii'iaterial may be used.

The base 9 of the spillwayhas an upstream deck-at. its'heel 11 with itslower portion 12 substantially vertical while the major portion 13thereof is upwardly inclined in a downstream direction to the crest 1%.The upper portion of the apron or fore slope 15 of the spillway has, inprofile, the common ogee curve. At the toe or downstream end of the foreslope, it is theusual practice to provide a solid curvedllillet orbucket which, as above stated, causes the overfalling water to bedischarged in a horizontal direction for the ostensible purpose ofprotecting the stream-bed against undercuttin'r and erosion at th lowerend of the toe.

In this novel invention there is provided a recessed or hollowed bucket16 atthe downstream toe and su hollowliucket extends substantially thewhole length of the spillway. that across the stream-bed occupied by thespillway. The over ial eu water may il -erein form a pool at thespillway toe and static pressure thereof opposes the dyic pressure otthe OVJllitllllng water as it e; rs the pool with the result that theswiftly moving; water is sudden slowed up and the water acquires adownstream direction of motionthroughout the full depth of the naturalstream within a short distance of the spillway toe.

lVhilethe hollow bucket maybe separate structure it is preferable toconstruct it as an integral part of the spillway strengtheninn" it witha plura v of s a'ed buttresses or cross-walls it). in r spillway of th'opposit the usual cross-walls 5Z0 the .1 i

' v structure. r unong the advanta es ral construction are a greaterease in designir or laying-out, a reduction in expense of construction,the spillway foundation is widened, a more uniform distribuend of therim 19, an apron 22 may be extended and this may be integral with thebucket or not, as desired, although it is here shown as the latter. Itmay be noted that the apron 22 is shown in the. drawings as beingunusually short for the spillway illustrated and such showing isintentional as the employment ofthe novel hollow bucket with itswater-slowing function permits the use 0i such inexpensive short apron.

The novel-undercutting of the fore slope of the spillway is also shownin Figure 1 wherein the lower portion of the fore slope 15 is re-entrantly designed to provid a recess 23 forming an upstreamcontinuation of the hollowbucket 16. Thus. this lmcket portion or recess23 extends upstream underneath the fore slope or downstream face of thespillway. The result of such shaping; of the bucketis to cause theformation of a back eddy behind the water swiftly descending into thebucket pool. Home, the overfalling water is attacked on the undersideand is more rapidly retarded and the greater the thickness of theoverfalling water, the more valuable becomes the undercut rece'ss 23.v

In the spillway' embodying the inve .ticn, the fore slope is shaped tolead the overfalling water, just before it enters the hollow bucketpool. in as nearly a vertical (lirect-ion as itsinitial horizontalvelocity and the structural features of the des n permit. The purpose tocause the dynan'iic pressure of the overtallinc' water to be exertedmore nearly directly in opposition to the static "pressure of the pool.

dam or spillway to be constructed.

While the precise dimensions of this novel hollow bucket may be variedfor difl'erent installations. the dimensions ot a particular bucket fora given installation are substantially correlated to the height of theselector: dam or spillwa-y, the amount of overflow and the natural depthof tail-water below the dam. In this art these three factors heightamount and depth) for any given instalIation. are always determined asaccurately as possible in advance of the designing of the IJllTO- wiseone skilled in this art, may quickly and easily determine with a curacyfor any proposed proiect the tltllJi'll'O'f tail-water which willprovide the static back-pressure neces sarvto destroy the excess energyof the overfalling water so that it will flow down the natural channelbelow the fall at the same depth and velocity as it naturally doeswithout the progected dam or spillway. Such predetermined de th of tailwater 1s hercm specified by D for sake of clarity and conciseness.Incident to the determining of the dimension I)" there is alsodetermined the thickness of the overfalling sheet of water assuming thatit has had an unobstructed fall to substantially the level of the centeroi gravity of the tail-water. Such prede termined thickness will beherein specified by T. The effective dimensioning of the hollow bucketis principally based upon such dimensions D' and Ti Therefore, incarrying out this novel method oi designing a SPlllYl'Ely for aparticular project or installation, there is first determined as closelyas possible the relation between the volume of water discharged. thedrop thereor, and the natural ater level below the dam for all flooddischarges. By all flood discharges is meant not only the maximum flooddischarge which the spill vay must ac connnodate' but also lesser flooddischarges which sometimes govern at least some of the dimensions of thenovel hollow bucket. The dimensions D and T are then deter mined for thevarious flood conditions. After determination oi such basic dimensions,the hollow bucket proportionately designed.

In the preferred form of hollow bucket, its downstream width from themedian plane of the overtalling water during the maximum flood dischargeis substantially equal. to said dimension D and never less thansubstantially one and a half tin'ies the thickness T oi the ovcrtalling'water during; ijnaxiniuni flood discharge as it enters the hollowbucket. The top of the hollow bucket at the upstream side is below thelevel of the tail-water (llll'll! maximum flood conditions and,particularly for the purpose of determining the dimension T ispreterably taken as substantially at the level of the center of gravityof the tail-water during maximum flood conditions. The bottom 17 of thebucket must be below the downstream rim 19 a distance greater than thethickness or widthTof the overfalling' water during maximum flooddischarge it enters the hollow bucket. The downstream rim ot the bucketis designed to be below the is it is prcwhich is adapted to a lesservein in this connection that, i

In the form of spillway shown in Figure 2, there is graphicallyillustrated the solid type of spillway adapted to discharge a 1 tiv'elylarger volume of water at a l sser drop than is shown in Figure 1 andthere is also suggested the shape of the novel hollow bucket res iltantfrom the application thereto of the teaching of this invention.

Figure 3 illustrates solid type spillway and a greater drop than isshown in Figure 2 but to a larger volume and only a slightly greaterdrop than is shown in Figure 1 The comparison of the shayes suggested ofhe hollow buckets respectively illustrated will aid those skilled in theart in visualizing readily the results obtained by the applicm tion ofthis invention to such variant l'orins of spillways.

The solid type of spillway is also shown in Figure 4 as well as in allthe remaining l ures. lhis'particular tigure illustrates a relativelyhigh spill ray and, from a comparison of the UHCJBl'CHtt ng extensionsof the buckets 111 the different e lanatory views, it will be noted thatas the height ot' the drop increases, the undercut portion is reducedbecause with increas and less desirable. v

The form sho vn in Figure known as the gate type and;-

r- (3 0 mm shown as entirely open, h l would have the same desirable{lCLlOll if tl gate were partially closed. The princi a dimension D forthis type of bncke should preferably be c onuguted upon 1hassumptionthat only part of the gates wil be opened a large amount thusdischarging a laro'e volume of water at one portion of the width of thespillway without a proportionate raising of the depth of tail-water 'wlich will thinly spread out over the down-' stream river bed. Under suchconditions the downstream rim of the bucket must be placed relativelylower than i't all of the gates were opened the same amount. In otherwords, when designing such. a hollow bucket, there will initially bedetermined the depth of tail-water over th rim which will provide theabove specified static back presure when only part of the gates opened.Such dimension D so obtained will obviously necessitate lowering the rimof the bucket below an elevation obtained from a computation fromconditions obtaining when all of the gates are opened.

Figures 6 and 7 are more particularly useful as illustrati -Fe of thenovel hollow bucket spillway wherein the bucket is reduced substantiallyto its minimum practicable dimensions while still carrying outtheobjects of the invention. It will be noted that Figure o {W767 hollowbucket 7 omits the undercut feature of tie bucke and as a result thecross-wallor buttress 10 is also omitted. On account of the upwardcurrents on the downstream side of thenovel hollow bucket 16, logs andother debris are deflected upward and'the tendency for such debris tostrike the downstream wall 18 ot the hollow bucket is minimized. Whenuser. as a part of the hollow bucket, the buttress 10 also acts todeflect logs,

other large floating debris, downstream. Such debris, however, can notlong lodge in the .l'il'ltlll eddy next to the dam as it will soon becaught by the downstream currents. Tfhere large quantities of logs mustbe passed over a spillway dam instead of through sluices special yprovided for that purpose the hollow bucket with slightly increasedcost, may advantageously be widened downstream, dependent upon thelength of ted in the given stream.

thus d scribed my invention what desire to secure by Letunderneath the 7downtrees, ice I having a portion exa. in a spi ray of the adherent'rappe type. a hollowl rcket having a portion extending upstretununderneath the downst cam face or" the spillway and the bottom bucketbein below the level of the.

wardly terminating below the level of the tail-inter correspondm toZHZLXEHHHH flood discl'nirge of the spillway.

. n a soillway of the adherent ,nappe dimensioned to proed dinjiension Dfor all 5 oi ow bucket having a portion CX- tend upstream underneath thedownllltl whereby some of the water pressure against the back of thespillway is carried to the foundation through said hollow bucket.

7. In a spillway of the adherent nappe type, a hollow bucket at thedownstream toe of the spillway, the bottom of the bucket being below thenatural level of the downstream bed, and a plurality of reinforcingmembers connecting the bucket with the front of the spillway making saidbucket an integral part thereof whereby some of the water pressureagainst the back of the spil way is carried to the foundation throughsaid hollow bucket.

8. In a spillway of the adherent nappe type, a hollow bucket at thedownstream toe of the spillway, said bucket having a portion extendingupstream underneath the downstream face of the spillway, and a pluralityof reinforcing members connecting the bucket with the front of thespillway making said bucket an integral part thereof whereby some of thewater pressure against the back of the spillway is carried to thefoundation through said hollow bucket.

9. In spillway of th adherent nappe type, a hollow bucket adjacent itsdownstream toe and extending substantially the length of the spillwayand a plurality of reinforcing members connecting the bucket and frontof the spillway making said bucket an integral part thereof whereby someof the water pressure against the back of the spillway is carried to thefoundation through said hollow bucket.

10. In a spillway of the adherent nappe type a hollow bucket adapted toconfine the surface eddy to the overfallen water above the bucket andthe bottom of the bucket having a depth below its downstream run 'atleast substantially equal to the specified dimension T for maximum flooddischarge and the downstream width of the bottom of the bucket being atleast equal to substantially twice the specified dimension T for maximumflood discharge, and said bucket having its downstream rim below thelevel of the tailnvater a distance at least equal to the specifieddimension D for all discharges of said spillway.

11. In a spillway of the adherent nappe type a hollow bucket adapted toconfine the surface eddy to the overfallen water above the bucket andthe bottom of the bucket being a depth below its downstream rim at leastsubstantially equal to the specified di mension T for maximum flooddischarge and the downstream width of the bottom of the bucket being atleast equal to substantially twice the specified dimension T for maximumflood discharge, said bucket haw ing a portion extending upstreamunderneaththe downstream face of the spillway, and also having itsdownstream rim below the level of the tail-water a distance at leastequal to the specified dimension D for all discharges of said spillway,and a plurality of reinforcing members connecting the bucket with thefront of the spillway making said hollow bucket an integral partstructurally and functionally of said spill vay structure.

A monolithic spillway having an adherent nappe face for the discharge ofthe o falling water, said spillway being formed with an integral hollowbucket at the downstream toe of the spillway and with the bottom of thebucket below the natural level of the downstream I'lVGldJCKl, and saidbucket having a portion extending upstream underneath the downstrean'iface of the spillway.

In witness whereof, I have hereunto set my hand. this 29th day ofDecember 1924- ADOLPH F. MEYER.

